Variety, the spice of life and essential for robustness in excitation energy transfer in light-harvesting complexes

Oh, Sue Ann; Coker, David F.; Hutchinson, D. A. W.

doi:10.1039/c9fd00081j

Cited by 5 publications

(6 citation statements)

References 35 publications

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“… 71 High-frequency intrapigment vibrations were also found to be important for energy transfer between high- and low-energy bilin chromophores in marine cryptophyte algae. 72 − 74 In these cases, where the energy difference between the minima of the PES of the excited states is large compared to the reorganization energy, a classical theory of nuclear motion would result in a too small rate constant. Larger reorganization energies occur in charge transfer reactions, because of the polar nature of the charge separated state.…”

Section: Discussionmentioning

confidence: 99%

“…Large energy gaps between chromophores occur, e.g., between chlorophyll b (Chl b ) and Chl a pigments in the major light-harvesting complex of higher plants LHCII, where high-frequency intrapigment vibrations were found to be essential for efficient Chl b → Chl a energy transfer . High-frequency intrapigment vibrations were also found to be important for energy transfer between high- and low-energy bilin chromophores in marine cryptophyte algae. − In these cases, where the energy difference between the minima of the PES of the excited states is large compared to the reorganization energy, a classical theory of nuclear motion would result in a too small rate constant. Larger reorganization energies occur in charge transfer reactions, because of the polar nature of the charge separated state.…”

Section: Discussionmentioning

confidence: 99%

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Semiclassical Modified Redfield and Generalized Förster Theories of Exciton Relaxation/Transfer in Light-Harvesting Complexes: The Quest for the Principle of Detailed Balance

Renger

2021

J. Phys. Chem. B

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A conceptual problem of transfer theories that use a semiclassical description of the electron-vibrational coupling is the neglect of the correlation between momenta and coordinates of nuclei. In the Redfield theory of exciton relaxation, this neglect leads to a violation of the principle of detailed balance; equal “uphill” and “downhill” transfer rate constants are obtained. Here, we investigate how this result depends on nuclear reorganization effects, neglected in Redfield but taken into account in the modified Redfield theory. These reorganization effects, resulting from a partial localization of excited states, are found to promote a preferential “downhill” relaxation of excitation energy. However, for realistic spectral densities of light-harvesting antennae in photosynthesis, the reorganization effects are too small to compensate for the missing coordinate–momentum uncertainty. For weaker excitonic couplings as they occur between domains of strongly coupled pigments, we find the principle of detailed balance to be fulfilled in a semiclassical variant of the generalized Förster theory. A qualitatively correct description of the transfer is obtained with this theory at a significantly lower computational cost as with the quantum generalized Förster theory. Larger deviations between the two theories are expected for large energy gaps as they occur in complexes with chemically different pigments.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Semiclassical Modified Redfield and Generalized Förster Theories of Exciton Relaxation/Transfer in Light-Harvesting Complexes: The Quest for the Principle of Detailed Balance

Renger

2021

J. Phys. Chem. B

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“…The second type of parameter is related to the efficiency of the allosteric process at a much longer time than that characteristic of the perturbation wave and it is associated with the average distribution of the perturbation in the sites. We have defined, as in literature [for example in LH process (Sue et al, 2020)] and in our previous studies (Ferretti et al, 1998;Ferreti et al, 2000;Villani, 2008), the perturbation transfer efficiency to a particular target (active) site |a> in terms of the time-averaged population of this site:…”

Section: Models Of Allosteric Phenomenonmentioning

confidence: 99%

A Time-Dependent Quantum Approach to Allostery and a Comparison With Light-Harvesting in Photosynthetic Phenomenon

Villani

2020

Front. Mol. Biosci.

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The allosteric effect is one of the most important processes in regulating the function of proteins, and the elucidation of this phenomenon plays a significant role in understanding emergent behaviors in biological regulation. In this process, a perturbation, generated by a ligand in a part of the macromolecule (the allosteric site), moves along this system and reaches a specific (active) site, dozens of Ångströms away, with a great efficiency. The dynamics of this perturbation in the macromolecule can model precisely the allosteric process. In this article, we will be studying the general characteristics of allostery, using a time-dependent quantum approach to obtain rules that apply to this kind of process. Considering the perturbation as a wave that moves within the molecular system, we will characterize the allosteric process with three of the properties of this wave in the active site: (1) t a , the characteristic time for reaching that site, (2) A a , the amplitude of the wave in this site, and (3) B a , its corresponding spectral broadening. These three parameters, together with the process mechanism and the perturbation efficiency in the process, can describe the phenomenon. One of the main purposes of this paper is to link the parameters t a , A a , and B a and the perturbation efficiency to the characteristics of the system. There is another fundamental process for life that has some characteristics similar to allostery: the light-harvesting (LH) process in photosynthesis. Here, as in allostery, two distant macromolecular sites are involvedtwo sites dozens of Ångströms away. In both processes, it is particularly important that the perturbation is distributed efficiently without dissipating in the infinite degrees of freedom within the macromolecule. The importance of considering quantum effects in the LH process is well documented in literature, and the quantum coherences are experimentally proven by time-dependent spectroscopic techniques. Given the existing similarities between these two processes in macromolecules, in this work, we suggest using Quantum Mechanics (QM) to study allostery.

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“…This energy transfer takes place through nature-designed molecular wires very efficiently [1,2] and robustly. [3][4][5][6] The importance of coherence has been well studied, along with an optimal choice of parameters governing efficient EET. [7][8][9][10] Further, the importance of the arrangement of chromophores [11][12][13] inside these natural molecular wires and the dynamics of energy transfer has been frequently pointed out and studied [6,[14][15][16][17][18][19][20][21][22] using different techniques.…”

Section: Introductionmentioning

confidence: 99%

Coherence and Efficient Energy Transfer in Molecular Wires: Insights from Surface Hopping Simulations

Sindhu

Jain

2022

ChemPhysChem

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Understanding the dynamics of electronic energy transfer through a molecular wire is essential to understand the working of natural processes like photosynthesis. We investigate simpler 2 and 3‐site model Hamiltonians in this work to understand the importance of coherence to efficient energy transfer. We compare the results of surface hopping simulation with that of numerically exact results and rate theories. Different parameters are analyzed, motivated by a photosynthetic molecular wire – the FMO complex. A comparison of results from different theories shows that coherence can play an important role towards efficient energy transfer for certain parameters. When these coherences are important, even small couplings (of the order of 5 cm−1) in the Hamiltonian can significantly affect rates. Surface hopping simulations capture all the results correctly qualitatively. Rate theories, on the other hand, can differ significantly from numerically exact results when coherences become important. The results of this work should provide design guidelines for efficient energy transfer in molecular wires.

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Variety, the spice of life and essential for robustness in excitation energy transfer in light-harvesting complexes

Abstract: We review our recent work showing how important the site-to-site variation in coupling between chloroplasts in FMO and their protein scaffold environment is for energy transport in FMO and investigate the role of vibronic modes in this transport.

Cited by 5 publications

References 35 publications

Semiclassical Modified Redfield and Generalized Förster Theories of Exciton Relaxation/Transfer in Light-Harvesting Complexes: The Quest for the Principle of Detailed Balance

Semiclassical Modified Redfield and Generalized Förster Theories of Exciton Relaxation/Transfer in Light-Harvesting Complexes: The Quest for the Principle of Detailed Balance

A Time-Dependent Quantum Approach to Allostery and a Comparison With Light-Harvesting in Photosynthetic Phenomenon

Coherence and Efficient Energy Transfer in Molecular Wires: Insights from Surface Hopping Simulations

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